Move to SPDX licenses (#449)

* Move to SPDX licenses

Found a way to do this without breaking API compat, so here it is, instead of waiting for v3

Resolves MOD-129
Resolves #396

* License URL updates

* what was I thinking

* Do a thing

* Add open source filter

* Remove dead imports

* Borrow

* Update 20220910132835_spdx-licenses.sql

* Add license text route

* Update migration

* Address comments

Cargo.lock

@@ -1566,6 +1566,7 @@ dependencies = [
  "serde_with",
  "sha1 0.6.1",
  "sha2 0.9.9",
+ "spdx",
  "sqlx",
  "thiserror",
  "tokio",
@@ -2781,6 +2782,15 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "spdx"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a346909b3fd07776f9b96b98d4a58e3666f831c9a672c279b10f795a34c36425"
+dependencies = [
+ "smallvec",
+]
+
 [[package]]
 name = "spin"
 version = "0.5.2"